{This is a stub}
For now:
http://www.therailsway.com/2007/9/3/using-activeresource-to-consume-web-services
http://ryandaigle.com/articles/2007/3/14/rest-activeresource
http://bloggingrailsconf.com/articles/2006/06/25/david-heinemeier-hansson-keynote
http://ryandaigle.com/articles/2006/06/30/whats-new-in-edge-rails-activeresource-is-here
http://blog.mauricecodik.com/2006/06/instant-rest-on-rails-activeresource.html
http://microformats.org/wiki/rest/rails
http://www.xml.com/lpt/a/2004/12/01/restful-web.html
http://weblog.techno-weenie.net/2006/12/12/taking-ares-out-for-a-test-drive
In Brazilian Portuguese:
http://www.balanceonrails.com.br/articles/2006/08/06/
http://www.balanceonrails.com.br/articles/search?q=p%C3%B3s-RailsConf%3A+Abrindo+caminho+para+Rails+1.2
There is a tutorial in the great book Rails Cookbook (chapter 6).
Also see Ryan Daigle’s presentation on it:
http://ryandaigle.com/articles/2006/08/01/whats-new-in-edge-rails-simply-restful-support-and-how-to-use-it